Wire stripper

ABSTRACT

A cutter blade is mounted in a cutter block such that the cutting edge of the blade intersects a series of transverse grooves in the block, the grooves being of various depths and widths to accommodate electrical wiring covered with insulation of differing thicknesses. A spring loaded arm maintains pressure on the wiring as the block is rotated around the conductor of the wiring to form an annular cut in the insulation of the wiring. The cut around the conductor ceases when the wiring bottoms out in the selected groove before the cutting edge can engage the conductor. The pressure arm is a part of a single length of rod material which also includes a coil to spring load the arm and a pair of hand grips to control the arm, one of the grips serving as a finger-receiving ring used to rotate the block.

United States Patent 1 Schlueter Apr.2,l974

[ WIRE STRIPPER Donald K. Schlueter, Box 40, Farley, Mo. 64028 [22] Filed: July 10, 1972 [21] Appl. No.: 270,092

[76] lnventor:

[52] US. Cl. 30/912 Primary Examiner.lames l... Jones, Jr.

Assistant Examiner-Mark S. Bicks Attorney, Agent, or Firm-Schmidt, Johnson, Hovey & Williams [5 7 ABSTRACT A cutter blade is mounted in a cutter block such that the cutting edge of the blade intersects a series of transverse grooves in the block, the grooves being of various depths and widths to accommodate electrical wiring covered with insulation of differing thicknesses. A spring loaded arm maintains pressure on the wiring as the block is rotated around the conductor of the wiring to form an annular cut in the insulation of the wiring. The cut around the conductor ceases when the wiring bottoms out in the selected groove before the cutting edge can engage the conductor. The pressure arm is a part of a single length of rod material which also includes a coil to spring load the arm and a pair of hand grips to control the arm, one of the grips serving as a finger-receiving ring used to rotate the block.

4 Claims, 7 Drawing Figures WIRE STRIPPER In all previously suggested wire strippers of which I am aware, it is virtually impossible, without extreme care and time-consuming attention, to effectively and consistently sever the insulation completely around the electrical conductor while, at the same time avoid all cutting, nicking, scratching or other damage to the conductor itself, causing a weakening such as to create a potentially troublesome point in the conductor. Almost any contact by the cutter with the metal conductor while the insulation is being cut will result in the danger of circuit breakage upon separation of the metal at the zone of damage resulting from stresses and strains, particularly vibration.

One area in which unusual painstaking and watchful concern becomes extremely important is in aircraft, employing thousands of circuits, many of which are critical from the standpoint of safety. Vibration is ever present, resulting in frequent circuit breakage, and in a very high percentage of such cases, the trouble occurs at the very area where insulation severence had taken place during installation Carelessness is a factor to be expected; therefore, the tool used by workmen must be most reliable, leaving no opportunity for error, misuse or failure.

Moreover,a completely satisfactory wire stripper, in addition to accuracy, must be easy to use, capable of permitting the task to be accomplished quickly, and small enough to be used in confined spaces and locations that are not readily accessible. Otherwise craftsmen will discard the tool in an effort to find a better way or use it in a manner which will not accomplish the perfection which is required. It is not unusual for trouble spotters and repairmen to spend many, many expensive hours in the location of but one break among the extremely large number of electrical wires in an airplane or other machines and instruments used commercially and in industry generally. Manifestly, in many areas, such as missiles, rockets, telemetry and other modern day instrumentation; subsequent repair cannot be considered; initial trouble-free installation must be critically absolute.

It is, therefore, the primary object of the present invention to provide a wire stripper which will meet all of the specifications above indicated and solve many, many problems heretofore presented through use of devices and methods heretofore devised for use or experimentation.

An important object of the present'invention is to provide a wire stripper which will accommodate a large number of wires of differing insulation thicknesses and, in each case, fully sever the insulation entirely around the conductor without contacting thelatter, and therefore, in complete absence of any damage thereto whatsoever.

Another important object of the present invention is to provide a wire stripper which incorporates a certain degree of automation in that the necessary pressure to cause full severence without conductordamage is not dependent upon the grip of the user which, of course, is variable and essentially impossible to control.

Still another important object of the present invention .is to provide a wire stripper which requires no skill of any kind on the part of the user and which will operate with'resultant perfection repeatedly over a long period of time, the only normal tasks being the simple insertion of the insulated wire in place and the spinning of the tool around the wire.

A further object of the present invention is to provide a small, safe, inexpensive, light weight, easy to use and manufacture wire stripper which may be conveniently and quickly manipulated in the smallest of available working spaces.

In the drawing:

FIG. I is a side elevational view of a wire stripper made according to the present invention;

FIG. 2 is a bottom view thereof;

FIGQ3 is a view showing the side thereof opposite to FIG. 1;

FIG. 4 is a top view thereof;

FIG. 5 is a cross sectional view taken on line 55 of FIG. 3; and

FIGS. 6 and 7 are cross sectional views taken on lines 66 and 77 respectively of FIG. 2.

The main components of the wire stripper shown in the drawing include an elongated cutter block 10, a cutter blade 12 and a single length of initially straight, slender spring rod 14. The rod 14 is formed into a coil 16 atone end of the block 10 having a pair of lengths 18 and 20 extending therefrom along the block 10 which, in turn, terminate in hand grips 22 and 24 respectively at the opposite end of the block 10.

The heads of a pair of removable fasteners 26, screw threaded into the block 10, releasably hold the length 18 within a channel 28 extending longitudinally along one face 30 of the block 10 and constitute the sole attachment of the rod 14 to the block 10. The length 20 of the rod 14 is in the nature of a swingable arm that is yieldably biased toward the longitudinal center line of the top 32 of the block 10 by the coil 16.

The channel 28 is L-shaped to also accommodate a leg 34 extending laterally from the length 18. The leg 34 terminates in the grip 22 which is in the nature of a loop that is disposed in a plane parallel with top 32 and bottom 36 of the block 10. The arm 20 has a leg 38 extending laterally in a direction opposite to the leg 34, and a depression in the proximal end of the block 10 receives a portion of the leg 38. The leg 38 termimates in the ring shaped grip 24 which may, as shown, be in the nature of a second coil that is essentially coplanar with the coil 16 and adapted to receive a finger of the-user of the wire stripper.

The top 32 of the block 10 has a series of transverse grooves 42 of various predetermined widths and depths, depending on the diameter of the electrical wiring 44 to be stripped of insulation 46 from the metallic conductor 48 thereof. The grooves 42 present alternate ribs 50 across the top 32 of the block 10 against which the arm 20 is held by the coil 16.

The elongated, perforated blade 12 is disposed in a slit 52 in the block 10 and has a longitudinal cutting edge 54 traversing the grooves 42 medially of the latter,

but projecting into the grooves 42 no farther than the thickness of the insulation 46. The fasteners 26 pass through the blade 12 and releasably clamp it in place within the slit 52. Small studs 56 (one only being shown) in the bottom 36 abut the base edge of the blade 12 to adjust the extent of protrusion of the edge 54 beyond the bottoms of the grooves 42. A pinreceiving hole 58 in the bottom 36 of the block 10 facilitates removal of the blade 12 for replacement purposes. Upon removal of the fasteners 26 insertion of such pin in the hole 58 aids in forcing the blade 12 out OPERATION The wire stripper is handled by inserting one finger through the grip 24 and pressing on the grip 22 with the thumb to move the grips 22 and 24 toward each other (see arrows in FIG. 1) and thereby swing the arm away from the grooves 42 as shown by dotted lines in HO. 1. The wiring 44 is then laid across the cutting edge 54 at the appropriate groove 42 as shown in FIG. 4, whereupon the thumb pressure on grip 22 is released, causing coil 16 to return the arm 20 to a position clamping the wiring 44 against the edge 54.

The tool is then rotated by the operator around the wiring 44 as the grip 24 rotates on his finger, causing the blade 12 to gradually effect an annular cut into the insulation 46 around the conductor 48 as the arm 20 maintains a pressure on the wiring 44. The cutting action ceases when the wiring 44 bottoms out in the groove 42 and at that time the insulation 46 is completely severed without the edge 54 having come into contact with the conductor 48. The cut-away and portion of the insulation 46 may then be stripped off the conductor 48 through use of the stripper or the arm 20 may be swung away to release the wiring 44 and the end portion stripped away by hand or otherwise.

in the tool chosen for illustration, insulation 46 having thicknesses which range from approximately 0.003 to 0.016 of one inch may be accommodated (see indicia 60) on wiring 44 having an outside diameter offrom about 0.007 to 0.1875 of one inch, but such dimensions for the grooves 42 are by way of example only. More important is the fact that the grooves 42 are chosen by the operator in accordance with insulation thickness rather than overall size of wiring 44 or diameter of conductor 48.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

l. A tool for cutting insulation surrounding metallic conductors of electrical wiring, said tool comprising:

a cutter block having a groove of predetermined width and depth;

a spring loaded arm carried by the block for pressing the wiring toward said groove; and

a cutter blade carried by the block and having a cutting edge disposed to cut the insulation as the tool is rotated about the wiring,

said block having a coil spring at one end thereof having a pair oflengths extending therefrom along the block,

said arm being one of said lengths and having a grip extending laterally therefrom in one direction, the other length having another grip extending laterally therefrom in the opposite direction,

said grips being at the opposite end of the block and squeezable toward each other to spring the arm away from the groove.

2. A tool as claimed in claim 1, wherein the block is provided with a series of grooves of predetermined widths and depths underlying said arm.

3. A tool as claimed in claim 2, wherein said blade traverses the grooves intermediate the ends of the latter, said edge of the blade being in aligned parallelism with said arm.

4. A tool as claimed in claim 1, wherein said grip on the arm is a finger ring essentially coplanar with said coil and about which the tool may be rotated. 

1. A tool for cutting insulation surrounding metallic conductors of electrical wiring, said tool comprising: a cutter block having a groove of predetermined width and depth; a spring loaded arm carried by the block for pressing the wiring toward said groove; and a cutter blade carried by the block and having a cutting edge disposed to cut the insulation as the tool is rotated about the wiring, said block having a coil spring at one end thereof having a pair of lengths extending therefrom along the block, said arm being one of said lengths and having a grip extending laterally therefrom in one direction, the other length having another grip extending laterally therefrom in the opposite direction, said grips being at the opposite end of the block and squeezable toward each other to spring the arm away from the groove.
 2. A tool as claimed in claim 1, wherein the block is provided with a series of grooves of predetermined widths and depths underlying said arm.
 3. A tool as claimed in claim 2, wherein said blade traverses the grooves intermediate the ends of the latter, said edge of the blade being in aligned parallelism with said arm.
 4. A tool as claimed in claim 1, wherein said grip on the arm is a finger ring essentially coplanar with said coil and about which the tool may be rotated. 